Article counting machine with means for preventing miscount of overlapping and irregularly shaped articles



July 30, 1968 c, KLAPES 3,395,269

ARTICLE COUNTING MACHINE WITH MEANS FOR PREVENTING MISCOUNT OFOVERLAPPING AND IRREGULARLY SHAPED ARTICLES 2 Sheets-Sheet 1 Filed March22, 1965 Y JINVENTOR F I G. 2 MICHAEL c. KLAPEs' ATTORNEY M. C. KLAPESJuly 30, 1968 ARTICLE COUNTING MACHINE WITH MEANS FOR PREVENTINGMISCOUNT OF OVERLAPPING AND IRREGULARLY SHAPED ARTICLES Filed March 22,1965 2 Sheets-Sheet. 2

QQZBQwT 2 5m mwhZDOQ 44.520 kwmmmm INVENTOR.

l MICHAEL C. KLAPES M EH i .yjaaw 7 ATTORNEY United States PatentARTICLE COUNTING MACHINE WITH MEANS FOR PREVENTING MISCOUNT OF OVERLAP-PING AND IRREGULARLY SHAPED ARTICLES Michael C. Klapes, Lynnfield',Mass., assignor to Delta Engineering Corporation, Melrose, Mass., acorporation of Massachusetts Filed Mar. 22, 1965, Ser. No. 441,539 16Claims. (Cl. 235-92) ABSTRACT OF THE DISCLOSURE An article countingmachine embodying a photocell activated counter adapted to accuratelycount articles which are irregularly shaped, include holes, or tend tooverlap in passing through the photocell station. Two complementaryarticle sensors each consisting of a light source and a photocell aredisposed and connected so as to generate a signal whose leading edgeoccurs when either light beam is interrupted by an article to be countedand whose trailing edge occurs when both beams are no longerinterrupted. The control circuit also generates article count pulseshaving a width corresponding to the average transit time of articlespast the sensors, the pulses being generated as a continuous train solong as one of the photocells is deprived of light.

This invention relates to article-counting machines and moreparticularly to an improved article-counting system.

The primary object of the present invention is to improve onarticle-counting apparatus of the kind described and claimed in U.S.Patent Re. 25,013, issued July 25, 1961, to E. G. Cleveland et al. forApparatus for Counting and Packaging Articles. Such apparatus involves alight beam positioned to be intercepted by articles moving in singlefile along a predetermined path, a photocell positioned to receive thebeam when it is not interrupted by a moving article, and an electroniccounter for counting the number of times the photocell is deprived ofthe light beam and actuating associated mechanism each time apredetermined count is reached. Experience has demonstrated that suchprior article-counting systems exhibit accuracy of a high order incounting solid symmetrically shaped articles but undergo a drop inperformance when handling articles which are irregularly shaped, includeholes, or tend to overlap.

Acordingly a more specific object of the present invention is to providean improved article-counting system which is consistent in accuracyregardless of the shape or size of the articles being counted.

Another specific object of the invention is to provide an improvedarticle-counting system whose operation is readily adjusted to countarticles of different sizes with equal accuracy.

Still another object of the present invention is to provide anelectronic article-counting system having simple manually adjustablemeans for modifying counter operation according to the size and shape ofparts to be counted.

Other objects and many of the attendant advantages of the presentinvention will become more readily apparent when reference is had to thefollowing detailed specification which is to be considered together withthe accompanying drawings wherein:

FIGS. 1A and 1B illustrate two different positions of a typical articlehandled by apparatus embodying the present invention;

FIG. 2 presents a plurality of wave forms illustrative of the countingproblem presented by the article of FIGS. 1A and 1B and the manner inwhich the problem is solved by the present invention;

FIG. 3 schematically illustrates an article-counting apparatus embodyingthe present invention; and

FIG. 4 illustrates an electronic counting system constructed accordingto the present invention.

Turning first to FIGS. 1A and 1B, there are presented two views of arectangular nut 2 having a circular aperture 4. Assume that this articleis to be moved by a conveyor 6 in the direction shown by the arrowthrough a thin horizontal light beam (represented in cross-section bythe circle 8). Assume also that the beam is directed at a photocell (notshown). It is believed to be apparent that if the nut is lying fiat asin FIG. 1A, the light beam would be interrupted for the full time thatit takes the nut to move through it. Hence the photocell would sense asingle beam interruption and would produce a single output pulse. On theother hand. if the nut is standing on edge as in FIG. 1B, the light beamwill not be blocked oif completely for the full transit time of the nut,but will be sensed by the photocell during the time that the aper ture 4is passing through it. Hence the photocell output would be two pulsesinstead of one in the manner shown by waveform A in FIG. 2 This tendencyto yield two pulses instead of one can be reduced by employing twoelectric eye systems displaced degrees from each other. The two electriceye systems complement each other and by appropriate circuitry they willproduce a single pulse for the article 2, regardless of whether it is onedge or flat. Such a pulse is represented by waveform B- of FIG. 2; theleading edge of the pulse is generated when any one beam is firstblocked off and the trailing edge occurs when both beams are no longerinterrupted. Hence the width of the pulse represented by waveform Bcorresponds to the transit time of the article in passing through theelectric eye zone. However, using two complementary electric eye systemsin this manner makes it possible for an erroneous count to occur whentwo articles overlap one another at adjacent ends. Waveform Cillustrates this problem. Since the trailing edge of the signal derivedfrom the dual electric eye system does not occur until both beams arerestored, the second overlapping article will prevent the trailing edgefrom occurring when the first article has left the electric eye zone andinstead will cause the pulse width to be extended by an amountcorresponding to the additional time required for the second article topass through the two beams. The extension of the pulse width caused bythe trailing overlapping article is indicated by the broken lineextension of waveform C.

The present invention overcomes the problem represented by waveform C bygenerating a pulse correspond ing to waveform B and utilizing means forrepeating that pulse if at the end thereof a particular signal derivedfrom the electric eye system has not expired or been terminated. Inessence, the present invention utilizes a system that generates acontinuous train of pulses D so long as a light beam is interrupted,with the width of each of the pulses D= corresponding to the averagetime that the phot0cell(s) are deprived of light by articles movingthrough the electric eye system.

Referring now to FIG. 3, the illustrated apparatus comprises aconventional bowl feeder 12 adapted to advance articles to a dischargechute 14 in response to the influence of a vibrator (not shown). Thechute is adapted to de- 3 l liver articles onto a moving endlessconveyor 16. Associated with the upper run of the endless conveyor aretwo guide members 18 and 20 which co-operate to align articles on theconveyor so that they will pass in single file to an electric eye systemidentified generally at 22. The articles pass through the electric eyesystem as they are discharged by the endless conveyor 16 into acollecting hopper 24. The collecting hopper is provided with a butterflyvalve 26 which is operated by a rotary solenoid sys tem 28. Theconstruction of the hopper is such that in one position of the butterflyvalve, e.g., the inclined position shown in FIG. 1, the articles areprevented from passing out of the open bottom end of the hopper by thebutterfly valve. On actuation of the rotary solenoid system 28, thebutterfly valve rotates to an almost vertical position so as to permitgravity discharge of articles from hopper 24 into a delivery chute 30.The latter may direct the articles to various types of apparatus. In theillustrated embodiment delivery chute 30 functions to direct articlesfrom the hopper 24 to a packaging machine wherein a continuously movingfolded web 32 is transformed into a series of packages 34 eachcontaining a group of articles delivered by chute 30. Various forms ofsealing mechanisms may be used to transform the folded moving web 22into packages. In the illustrated embodiment, the sealing mechanismcomprises a pair of L shaped bars 36 disposed on opposite sides of themoving web. These bars are moved (by means not shown) into and out ofengagement with the web, forming a transverse seal 38 and a longitudinalseal 40 each time they engage the web.

The electric eye system 22 comprises at least one and preferably twophotocells 42A and 42B disposed at right angles and positioned toreceive beams generated by light sources 44A and 44B respectively. Theelectric eye system 22 and the rotary solenoid system 28 are connectedby suitable cables 46 to an electronic counter 48. Each time the lightbeams are broken by a part dropping from the moving belt, a count isregistered by the counter. The counter can be set by appropriate controldials 50 to emit an output control pulse to the rotary solenoid system28 when a predetermined number of counts have been registered. The pulsetransmitted to the rotary solenoid 28 is of sufficient amplitude andduration to cause the butterfly valve to move to its article dischargingposition and maintain it there just long enough to allow discharge ofall of the articles held in the hopper. The butterfly valve returns toits original position in time to catch the next article discharged fromthe conveyor.

To the extent described the apparatus of FIG. 3 is conventional and,except for the use of dual light beams, is substantially similar to theapparatus of said US. Patent Re. 25,013. However, it also differsmaterially from the patented apparatus in that the counter 48 includesthe system of FIG. 4 which provides a mode of operation consistent withwaveform D.

FIG. 4 illustrates a system adapted to produce the result represented bywaveform D. Turning now to FIG. 4, the illustrated system compriseseight transistors Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8. The collector oftransistor Q1 is connected to a positive voltage source V1. The base ofQ1 is connected to the same voltage source via a resistor 52. The baseis also connected to ground via two series connected photodiodes 54 and56. These photodiodes correspond to the photocells 42A and 42B. Theemitter of transistor Q1 is connected via two series connected diodes 58and 60 and a resistor 62 to ground. The junction of diodes 58 and 60 isconnected to the base of transistor Q2. The emitter of transistor Q2 isconnected to the junction of diode 60 and resistor 62 by way of a diode64. The junction of diode 60 and resistor 62 is also connected to thepositive voltage source V1 by way of a suitable resistor 66. The base oftransistor Q2 is connected to a negative voltage source V2 by way ofanother resistor 68. The collector of Q2 is connected to the samenegative voltage source by way of another resistor 70. The collector Iof transistor Q2 is also connected to the base of transistor Q3 by wayof a resistor 72. The base of transistor Q3 is also connected to thepositive voltage source V1 by way of a resistor 74. The emitter of thesame transistor is connected to ground and its collector is connected tothe negative voltage source V2 by way of a resistor 76. The collector oftransistor Q3 also is connected to two different two position switchesS1 and S2. Switch S1 has two sta tionary contacts 78 and 80 and amovable contact 82. The corresponding contacts of switch S2 areidentified as 84, 86, and 88 respectively. In one case the collector ofQ3 is connected by a resistor 90 to terminal 78 of switch S1; in theother case it is connected to terminal 86 of switch S2 via a resistor92. The movable contacts of the two switches are ganged together.

The junction of resistor 90 and switch contact 78 is connected by way ofa resistor 94 to the positive voltage source V1.

The movable contact 82 of switch S1 is connected to the base oftransistor Q4, withthe emitter of the latter connected to ground. Thebase and collector of transistor Q4 are connected by way of resistors 98and 100 respectively to the negative voltage source V2. The collector oftransistor Q4 also is connected to a pre-settable digital counter unit102 which drives an indicator unit 103 and also a relay 104-thatcontrols operation of the rotary solenoid system 28. The counter andindicator units are both conventional and form part of the electroniccounter 48 of FIG. 3,-The counter is of the type that emits an outputand restores itself to zero when a predetermined count is reached.

The movable contact 88 of switch S2 is connected to the base oftransistor Q5. The collector of transistor Q5 is connected by way of aresistor 106 to positive voltage source V1. The collector of Q5 is alsoconnected by way of a capacitor 108 and a parallel resistor 110 to thebase of transistor Q6; that same base is connected by way of a resistor112 to negative voltage source V2. The base of Q5 is connected by aresistor 114 to negative voltage source V2. The emitters of bothtransistors Q5 and Q6 are coupled together and connected by way of apair of series resistors 116 and 118 to negative voltage source V2. Thecollector of transistor Q6 is connected to positive voltage source V1via a resistor 120; it also is connected (a) directly to contact 80 ofswitch S1 and (b) to the base of transistor Q5 by way of a capacitor 122and a parallel resistor 124. Capacitor 122 and resistor 124 have thesame values as capacitor 108 and resistor 110 respectively. Resistor 120is equal in value to resistor 106.

Transistor Q7 has its collector connected to the collector of Q6 by wayof a diode 128 and also to negative voltage source V2 by way of acapacitor 130. The emitter of transistor Q7 is connected by a fixedresistor 132 and a variable resistor 134 to positive voltage source V1.Its base electrode is connected to the junction of two resistors 136 and138. The opposite end of resistor 136 is connected to ground while theopposite end of resistor 138 is connected by way of diode 140 topositive voltage source VI. A fixed resistor 142 is connected acrossresistor 138. Due to the current path afforded by Q7, the symmetricalcircuit including Q5 and Q6 is unbalanced and, in the absence of aninput signal at the base of Q5, the latter is off and Q6 is normallyconducting.

The junction of capacitor and the collector of transistor Q7 isconnected to theemitter of transistor Q8. The latter is of theunijunction type, having one base electrode connected back to thejunction of resistors 116 and 118, while the other base electrode isconnected by a resistor 134 to positive voltage source V1.

The foregoing electronic system comprises several dis crete stages. Thetransistors Q1 and Q2 and the related circuitry. form a detector stage;the transistor Q3 and related circuitry form a pulse shaper; thetransistors Q5 and Q6 form together with transistor Q7 a gatedoscillator that includes transistor Q8 as a reset pulse generator; the

transistor Q4 constitutes an output amplifier stage. The switches S1 andS2 make it possible to provide the output of the pulse shaper Q3directly to the amplifier Q4 or to the gated oscillator, whereupon theoutput of the gated oscillator in turn is fed back to the amplifier Q4via the switch contact 80.

Operation of the system when the switches S1 and S2 are in the positionshown in FIG. 4 is straightforward. So long as the light beams impingeon photodiodes 54 and 56, they conduct current to ground and therebymaintain transistor Q1 in a non-conducting condition. However, as soonas one of the photodiodes is deprived of light, the base of transistorQ1 is no longer coupled directly to ground and will rise to a voltagedetermined by the magnitude of resistor 52. The base voltage will risepositively and in so doing will cause transistor Q1 to conduct. It is tobe noted that the input signal voltage to Q1 produced by momentaryinterruption of a light beam by a moving article, is substantiallyrectangular in shape. The diodes 58 and 60 serve clamping and limitingfunctions while the diode 64 is essential for proper biasing oftransistor Q2. Accordingly the resulting positive voltage pulsedeveloped across resistor 62 also is substantially rectangular and has awidth proportional to the time that the light beam is interrupted. Thispositive pulse causes Q2 to produce a negative voltage pulse at the baseof transistor Q3. When this occurs, a positive rectangular voltagechange occurs at the collector of Q3. The positive pulse appearing atthe collector of transistor Q3 is applied by way of contact 78 of switchS1 to the base of transistor Q4, causing the latter to generate anegative pulse as an input to the counter unit 102. The width of theinput pulse to the counter unit is determined by the time thattransistor Q1 is on, and this in turn depends upon the length of timethat one of the light beams is interrupted by a passing article. Whilenot shown, it is to be understood that the input stage of the counter isadapted to respond to the positive going excrusion of the pulse derivedfrom the collector of transistor Q4 (which corresponds to therestoration of the light beam) and to register a count each time such anexcursion occurs.

The foregoing mode of operation is altered when the switches S1 and S2are reversed so that their movable contacts close on contacts 80 and 86respectively. With the switches reversed, the gated oscillator isinterposed between pulse shaping transistor Q3 and transistor Q4. Thusthe rectangular positive pulse that appears at the collector oftransistor Q3 when an article interrupts the light beam, is applied tothe base of transistor Q5. This positive input causes the collector oftransistor Q5 to become negative, thereby producing a negative pulse atthe base of transistor Q6. When this occurs, transistor Q6 flips olfwhile the transistor Q5 flips on. This reversed state of operation willexist for a predetermined time and then Q5 and Q6 will be restored totheir original states. If at the time they are restored to theiroriginal states the input signal still exists, they will immediatelyflip again to their previous reversed state for the same predeterminedtime. Thereafter they will be restored to their original states wherethe reversal may or may not reoccur, depending upon the presence orabsence of the input signal. The exact time that the flip flop is in theon condition depends upon the RC circuit provided by capacitor 130 andresistors 134 and 136 operating through transistor Q7. Capacitor 130charges through transistor Q7 when transistor Q6 is non-conducting,i.e., when the collector of transistor Q6 is at a high voltage. Whencapacitor 130 has charged to a predetermined level, the unijunctiontransistor Q8 fires and produces a sharp reset pulse, i.e., a spike,which is applied to the emitters of transistors Q5 and Q6 via resistor116. The output spike from transistor Q8 is much larger in amplitudethan the input signal pulses received by Q5; hence it will override anysuch input signal and cause both transistors to return to their originalstates. However, if when the reset pulse has passed, the base oftransistor Q5 still has an input signal voltage applied to it, the'flipflop will immediately reverse itself again. The flip flop will continueto undergo resetting and reversal so long as an input pulse is appliedto the base of transistor Q5. After the input signal has expired, itwill stay reset.

Changing the setting of resistor 136 alters the charging time ofcapacitor 130. The setting of resistor 136 varies with the length of thepieces or parts to be processed by the machine. The longer the length ofthe pieces to be counted, the more of resistor 136 must be tapped off.Conversely, the shorter the piece the smaller the effective value ofresistor 136 required to be coupled in series with capacitor 130. Inpractice the variable resistor 136 is a multiturn potentiometer operatedby a dial 150 provided on the front panel of the electronic counter 48(FIG. 3). The dial 150 is calibrated in inches and fractional partsthereof, e.g., tenths, 'hundredths, etc. so as to facilitate adjustmentby the machine operator of the charging time of capacitor to correspondto the length of the articles to be counted.

The number of reversals of the flip flop is sensed by counter unit 102.This is achieved by the coupling effected between the collector oftransistor Q6 and the base of transistor Q4 by switch S1. A test jack152 (FIG. 4) permits sampling the output of the oscillator so as to teston time of transistor Q6 as determined by the RC charging circuit thatoperates transistor Q8.

In addition to the improvement in results which it provides, aparticular advantage of the system of FIG. 4 is that it can beincorporated with minimum cost in existing article-counting apparatus,as for example, the apparatus described and claimed in reissue PatentNo. Re. 25,013. If desired, only one light beam and photocell may beused in place of the dual system embodied in the illustrated apparatus.Because the system is essentially an information rather than a powerhandling system, it lends itself well to printed circuit board design;this means not only economy of space but also ease of maintenance. Aprinted circuit board can be removed and replaced by another boardcontaining the identical circuitry, within a few minutes time.

A furthr advantage of the system of FIG. 4 is that the counter andindicator units may be of conventional design. Thus, for example, theindicator unit may be of the type employing Nixie tubes. By using aresettable counter, the relay 104 will be actuated each time the countreaches a predetermined amount, and will restore itself after apredetermined time interval so as to cause the solenoid system 28 tooperate in the manner previously described. It is also contemplated thatthe hopper 24 may be designed so that its butterfly valve does not stopor interrupt movement of articles through the hopper but simply divertsflow.

Of course, it is to be understood that the invention is not limited inits application to the details of construction and arrangement of partsspecifically described or illustrated, and that Within the scope of theappended claims, it may be practiced otherwise than as specificallydescribed or illustrated.

I claim:

1. An article counting system comprising means for transporting articlesof a given length in serial fashion past a predetermined point, meansfor directing a beam of radiant energy through said point so as to beinterruptible by articles passing through said point, means forproducing an output signal commencing with interruption of said beam andhaving a period substantially equal to the time that said beam remainsinterrupted, means responsive to said output signal for producing apulse train commencing substantially simultaneously with said outputsignal wherein each pulse is of fixed duration substantially equal tothe average transit time of an article through the beam, said pulsetrain terminating responsively to the termination of said output signalwhereby when a plurality of said articles continuously interrupts saidbeam a pulse train is produced having a number of pulses equal to thenumber of beam-interrupting articles, and means for counting saidpulses.

2. An article counting system as defined by claim 1 further includingmeans for modifying the duration of said pulses so that said system maybe used to count articles having a length different than said givenlength.

3. An article counting system as defined by claim 2 wherein saidlast-mentioned means is calibrated in units of length of articles to becounted.

4. An article counting system comprising means for transporting articlesof a given length in serial fashion past a predetermined point, firstmeans for directing a beam of radiant energy so as to be interrupted byarticles passing said point, second means for sensing when said beam isinterrupted by an article passing said point, third means responsive tosaid sensing means for producing an output signal each time said beam isinterrupted with said output signal having a time duration proportionalto the time of interruption of said beam, fourth means responsive tosaid output signal for generating pulses each equivalent in pulse widthto the average transit time of single articles through said beam, saidfourth means being adapted to terminate generation of said pulses inresponse to termination of said output signal, and fifth means forcounting said pulses as they occur.

5. An articles counting system as defined by claim 4 wherein said fourthmeans includes means for varying the width of said pulses so that saidsystem may be used to count articles having a length different than saidgiven length.

6. An article counting system as defined by claim 4 including sixthmeans for directing a second beam of radiant energy so as to beinterrupted by articles passing said point, and seventh means forsensing when said second beam is interrupted by an article passing saidpoint, and further wherein said third means is responsive to saidseventh means as well as said second means so that said output signal isproduced upon interruption of either beam.

7. An article counting system as defined by claim 6 wherein said firstand sixth means direct beams of light and said second and seventh meanscomprise first and second photodiodes connected in series, and furtherwherein said third means is connected to said photodiodes so as toproduce an output signal whenever one of said photodiodes is deprived oflight as a result of interruption of one of said beams.

8. An article counting system as defined by claim 7 wherein said thirdmeans comprises a multi-electrode variable impedance device having oneof its electrodes connected in series with said photodiodes and meansbiasing said device so that it is in a relatively low current conductingstate so long as said light beams impinge on both of said photodiodesand assumes a relatively high current conducting state when at least oneof said light beams is prevented from impinging on at least one of saidphotodiodes as a result of interruption by one of said articles.

9. An article counting system as defined by claim 8 wherein said deviceis a transistor having a base electrode connected in series with saidphotodiodes, and further wherein said output signal is produced inresponse to a change in current through said transistor.

10. An article counting system as defined by claim 4 further includingmeans for collecting articles downstream of said point, and means forreleasing said articles when the number of pulses counted has reached apredetermined value.

11. An article counting system as defined by claim 4 wherein saidcounting means comprises a counter that resets to zero when the numberof articles counted reaches a predetermined value.

12. An article counting system comprising means for transportingarticles in serial fashion through a predetermined discharge point at asubstantially constant speed, means for directing a beam of radiantenergy through said point, means for sensing said beam of radiantenergy, means connected to said sensing means for producing an outputsignal of predetermined polarity whenever and so long as said beam isinterrupted, first and second variable impedance current conductingdevices connected for flipflop operation, means for applying said outputsignal to said first device so as to cause it to undergo a first changein conduction, means for causing said second device to undergo a secondopposite change in conduction at the same time as said first deviceundergoes said first change in conduction, means responsive to saidsecond opposite change in conduction for generating and applying to atleast one of said devices after a time interval equal approximately tothe time that said beam is interrupted by an article passing throughsaid discharge point at said speed a sharp reset signal pulse having anamplitude sufficient to cause said devices to change back to theiroriginal conduction states notwithstanding continued application of saidoutput signal to said first device, said devices being adapted to remainin said original conduction states on expiration of said reset signalpulse if said output signal has previously terminated, and meansconnected to one of said devices for registering a count representativeof a single article each time said one device is restored to itsorignial conduction state.

13. An article counting system as defined by claim 12 includingadditional means for directing a second beam of radiant energy throughsaid point at an angle to said first beam and additional means forsensing said second beam of radiant energy, further wherein said meansfor producing said output signal is responsively connected to saidadditional sensing means so that said output signal is produced wheneverand for so long as at least one beam is interrupted.

14. An article counting system comprising means for delivering articlesof given length in serial fashion through a predetermined location at agiven speed, means for establishing a field of radiant energy directedso that it is attenuated by articles passing through said location,means for sensing attenuation of said field and producing asubstantially rectangular signal of predetermined polarity with a periodcorresponding to the time that said field is attenuated, pulsegenerating means responsive to an input signal for producing a pulsetrain commencing substantially simultaneously with said input signalwherein each pulse is of fixed duration substantially equal to the timethat said field is attenuated by an article passing through saidlocation at said speed, said pulse train tenminating responsively to thetermination of said input signal whereby the number of pulses in saidtrain is determined by the period of said input signal, means forapplying said rectangular signal as an input to said pulse generatingmeans, an amplifier with input and output terminals, means for applyingsaid pulse train to the input terminal of said amplifier, a counter withan input terminal, and means connecting the output terminal of saidamplifier to the input terminal of said counter for applying the outputof said amplifier to said counter so that said counter registers a countin response to each amplified pulse received from said amplifier.

15. An article counting system as defined by claim 14 wherein saidcounter is adapted to respond to the trailing edge of each amplifiedpulse.

16. An article counting system as defined Iby claim 15 further includingselectively operable means for applying said rectangular signal as aninput to said amplifier in stead of to said pulse generating means, sothat said counter registers a count in response to the trailing edge ofsaid rectangular signal.

(References on following page) 9 10 References Cited 3,290,488 12/ 1966Sewell 23592 S1mm0ns X Re. 25,013 7/1961 Cleveland 53- 1 MAYNARD R.WILBUR, Primary Examiner.

3,035,478 5/1962 Laycak 235-92 3,222,979 12/1965 Webster 250-223X 5MAIER Examme"

